Molecular Dipole Chains II

A simple one-dimensional dipole chain model is studied to explore the excitations and dissipation of kinetic energy in stacked planar molecular chains. At low temperatures, local dipole-dipole interaction dominates the properties of the chain. The analytic approximation agrees with molecular dynamics simulation for the low energy excitation spectrum, where acoustic mode behavior of the harmonic crystal lattice is obtained. Comparisons between antiferromagnetic and ferromagnetic dipole chains are made, and the important role of local dipole - dipole interaction is suggested. With antiferromagnetic interaction, the energy propagation occurs in three processes, while the secondary oscillation is no longer distinguishable with ferromagnetic interaction. Thermal equilibrium properties are discussed including the temperature fluctuation, dipole - dipole time correlation function, the Fourier density of correlation function, and the dispersion relation.